1. Field of Invention
This invention relates to non-planar sputter targets having crystallographic orientations promoting uniform deposition of sputtered material onto a substrate and methods of making the same.
2. Description of Related Art
Cathodic sputtering is widely used for depositing thin layers or films of materials from sputter targets onto substrates. Basically, a cathode assembly including the sputter target is placed together with an anode in a chamber filled with an inert gas, preferably argon. A substrate is positioned in the chamber near the anode with a receiving surface oriented normal to a path between the cathode assembly and the anode. A high voltage electric field is applied across the cathode assembly and the anode causing electrons to eject from the cathode assembly and ionize the inert gas. The positively charged ions of the inert gas are then propelled against a sputtering surface of the sputter target due to the electric field. The ion bombardment against the sputtering surface of the target causes portions of the material of the sputtering surface to dislodge from the sputter target surface and deposit as a thin film or layer on the receiving surface of the substrate at an opposite end of the chamber.
Recently, non-planar sputter targets have been developed to provide improved sputtering and deposition uniformity. For example, open-ended cup-shaped hollow cathode magnetron (HCM) sputter targets have been developed, as disclosed in U.S. Pat. No. 6,419,806 of common assignment herewith, the disclosure of which is incorporated herein by reference. These cup or pot shaped targets are generally comprised of a high purity metallic material as the target surface and are typically formed from well-known metal-working operations such as hydroforming. The closed end of the cup-shaped target comprises a dome. Sidewalls extend from the dome to an open end of the target. The application of heat and other manipulations that may be used to form the cup-shaped targets often cause changes in the microstructure or crystallographic orientation of the materials comprising the sputter target surface. Such changes may adversely affect the deposition of sputtered materials onto the substrate.
A need in the art exists for methods of making sputter targets of desired crystallographic orientation and for targets made by such methods wherein the targets, upon sputtering, result in improved coating uniformity.